Thanks for the link. One of the projects I'll probably never get around to is a thermoelectric-augmented fan coil unit for air-to-water heat pump retrofits. The existing emitters (and crucially the in-wall distribution piping that's expensive to insulate and vapor seal after the fact) would stay just above the dew point, and then the augmented fan coil would work to remove latent heat (humidity) by dropping a bit below the dew point via thermoelectric coolers that reject heat into the return piping.

It's a relatively small delta-T and in most climates a relatively small fraction of the overall cooling load, so it might just barely pencil out.